WASHINGTON/SAN JUAN, Puerto Rico, Oct 3 (Reuters) - P resident Donald Trump flew to Puerto Rico on Tuesday to view the havoc wreaked by Hurricane Maria and meet residents, many of whom are frustrated and resentful that they are still struggling with basic necessities two weeks after the storm.

The trip gives Trump the chance to show solidarity with survivors and demonstrate how his government intends to help them recover after they were hit by the worst hurricane in 90 years.

But it comes after he lashed out at San Juan Mayor Carmen Yulin Cruz for "poor leadership" on the weekend after she criticized his government's response. He said some people on the island "want everything to be done for them."

The White House invited Cruz to participate in Trump's visit but it was not immediately clear whether she had accepted.

Before leaving Washington on Tuesday morning, Trump told reporters that roads were cleared and communication capabilities were coming back on the island. He said the mayor had "come back a long way" since her criticism.

Trump had criticism of his own about the local response.

"Their drivers have to start driving trucks," he said at the White House. "So on a local level, they have to give us more help. But I will tell you, the first responders, the military, FEMA, they have done an incredible job in Puerto Rico."

The economy of the U.S. territory, home to 3.4 million people, already was in recession and its government filed for bankruptcy in May. The storm wiped out the island's power grid, and less than half of residents have running water.

Two weeks after Maria, it is still difficult for residents to get a cell phone signal or find fuel for their generators or cars. About 88 percent of the cellphone sites are still out of service.

Valentine Navarro, 26, a salesman in San Juan, shrugged off Trump's trip as a public relations exercise.

"I think hes coming here because of pressure, as a photo-op, but I dont think hes going to help more than he has already done and thats not much," Navarro said.

Puerto Rican Governor Ricardo Rossello said that as Trump flies over the island he would see "the magnitude of the devastation." He said there were 320 functioning cash machines across the island and that waiting times for gasoline had dropped significantly.

Angel Negroni, 72, of Juana Matos was trading his neighborhood's restored municipal water for ice made by a friend's generator-powered freezer.

Conditions on the island were slowly improving, he said.

"It's better now," Negroni said while standing on his covered porch, cooking fish in a propane-powered camping stove. "We're OK."

TRUMP TO ASK FOR $13 BILLION

Trump got high marks for his handling of Hurricane Harvey in Texas and Hurricane Irma in Florida and the Caribbean.

Caught off guard by the severity of Hurricane Maria's damage to Puerto Rico, Trump did not focus on the storm for days, instead launching a barrage of tweets over his view that National Football League players should be required to stand during the U.S. national anthem.

A previous Republican president, George W. Bush, faced widespread criticism for his administration's initial handling of Hurricane Katrina, which killed some 1,800 people in and around New Orleans in 2005.

Images of Trump standing together with mayors, the governor and federal officials would go a long way toward showing Americans the White House is addressing the hurricane damage, said retired Coast Guard Admiral Thad Allen.

Allen, who led the federal response to Hurricane Katrina and the Gulf oil spill, said the presidential visit will provide a chance to communicate that Americans care about the disaster on the isolated island territory.

But he warned against rhetoric that downplayed the challenges ahead or overstated accomplishments.

"Piling superlatives on work that is yet to be completed is not helpful," Allen said in an interview. "What you need is transparent, credible, open communication with the American people."

Trump should offer specifics to Puerto Ricans to give hope so they can begin planning how to rebuild, said Lars Anderson, who was a senior Federal Emergency Management Agency official in Democratic President Barack Obama's administration.

"He needs to talk about what exactly does his administration plan to do: how are they going to rebuild Puerto Rico? How are they going to deal with the fact that there are parts of Puerto Rico that arent going to get power for six months?" said Anderson, who now runs a crisis communications firm called BlueDot Strategies.

Trump's administration has transferred more than $20.5 million in federal funds to Puerto Rico to defray disaster expenses, FEMA said on its website.

The administration is preparing to ask Congress for $13 billion in aid for Puerto Rico and other areas hit by natural disasters, according to congressional sources said.

But that money will only go so far. The island's recovery will likely cost more than $30 billion.

"I dont see how, without significant federal support, that you dont find a situation where hundreds of thousands of people leave, and it could potentially be debilitating for years to Puerto Rico, said Jason Miller, who had led efforts to address the crisis at the National Economic Council during the Obama administration.

(Reporting by Roberta Rampton in WASHINGTON and Gabriel Stargardter in SAN JUAN, Puerto Rico; Additional reporting by Jeff Mason; Editing by Catherine Evans and Bill Trott)